1. Field of the Invention
The present invention relates to a pressure gauge having pressure range indicating needles.
2. Discussion of Related Art
FIGS. 5A to 5C show a conventional pressure gauge having an internal device (not shown) in a pressure gauge body 1, together with a pressure scale plate 2, a pointer 3 and pressure range indicating needles 4. The internal device converts a fluid pressure into a corresponding movement of the pointer 3 to indicate the pressure by the position of the pointer 3. The pressure range indicating needles 4 are movable and capable of being held in desired positions, respectively. A cover 5 is detachably attached to the front of the pressure gauge body 1. FIG. 5B shows the pressure gauge from which the cover 5 has been detached. As shown in the figure, the pressure gauge body 1 has two retaining grooves 6. The cover 5 has two hooks (not shown) on the reverse side thereof. The hooks are engaged with the retaining grooves 6 to attach the cover 5 to the pressure gauge body 1. The pressure range to be maintained depends on the object for which the pressure measurement is carried out, and also depends on the way in which the pressure gauge is used. Therefore, when the pressure range is to be changed, the cover 5 is detached from the pressure gauge body 1, and the pressure range indicating needles 4 are moved along the pressure scale plate 2. When the cover 5 is to be detached, as shown in FIG. 5A, the cover 5 is rotated counterclockwise through about 15 degrees to cancel the engagement between the hooks of the cover 5 and the retaining grooves 6 of the pressure gauge body 1, and the hooks are removed from the large-width portions of the retaining grooves 6. When the cover 5 is to be attached, it is laid over the pressure gauge body 1 in the position shown in FIG. 5A, and the hooks are inserted into the large-width portions of the retaining grooves 6. Then, the cover 5 is rotated clockwise through about 15 degrees to engage the hooks with the small-width portions of the retaining grooves 6.
Thus, the conventional pressure gauge requires the following operations to move the positions of the pressure range indicating needles 4. First, the cover 5 is removed by rotating it through about 15 degrees. Then, the pressure range indicating needles 4 are moved to respective set positions by using the tip of a screwdriver or the like. Thereafter, the cover 5 is laid over the pressure gauge body 1 in the position shown in FIG. 5A, and the hooks are inserted into the large-width portions of the retaining grooves 6. Then, the cover 5 is rotated clockwise through about 15 degrees. Thus, the conventional pressure gauge requires a great deal of labor to detach and reattach the cover 5 (for instance, it is not easy to insert the hooks of the cover 5 into the large-width portions of the retaining grooves 6 of the pressure gauge body 1). The cover 5 may be lost or damaged during the operation of detaching and reattaching the cover 5. When a plurality of pressure gauges are disposed adjacent to each other as shown in FIG. 5C, the cover 5 cannot be rotated because it contacts the cover 5 of the adjacent pressure gauge. Therefore, the cover 5 cannot be detached from the pressure gauge body 1.
A first object of the present invention is to provide a pressure gauge having pressure range indicating needles wherein the positions of the pressure range indicating needles can be moved without detaching the cover from the pressure gauge body.
A second object of the present invention is to provide a pressure gauge having pressure range indicating needles wherein the positions of the pressure range indicating needles can be moved even when a plurality of pressure gauges are disposed adjacent to each other.
To attain the above-described objects, the present invention is applied to a pressure gauge having an internal device, a pointer, a pressure scale plate and pressure range indicating needles, which are provided in a pressure gauge body. The internal device converts a fluid pressure into a corresponding movement of the pointer to indicate the pressure by the position of the pointer. The pressure range indicating needles are movable and capable of being held in desired positions. In addition, a cover is detachably attached to the front of the pressure gauge body.
According to a first arrangement of the present invention, a window hole is formed in the cover, and a transparent cover plate is fitted in the window hole of the cover in such a manner as to be capable of being opened and closed, so that when the transparent cover plate is open, the pressure range indicating needles are movable.
According to a second arrangement of the present invention, the cover and the transparent cover plate in the first arrangement are arranged as follows. A portion of the transparent cover plate near one end thereof is engaged with a portion of the cover near one end of the window hole, whereby the transparent cover plate is rotatably fitted. In addition, a portion of the transparent cover plate near the other end thereof is retainable by a portion of the cover near the other end of the window hole.
According to a third arrangement of the present invention, the cover and the transparent cover plate in the second arrangement are arranged as follows. An engagement recess is formed on the cover near one end of the window hole, and an engagement projection is formed on the transparent cover plate near one end thereof. In addition, a retaining recess is formed on the cover near the other end of the window hole, and a retaining projection is formed on the transparent cover plate near the other end thereof.
According to a fourth arrangement of the present invention, the cover and the transparent cover plate in the second arrangement are arranged as follows. An engagement projection is formed on the cover near one end of the window hole, and an engagement recess is formed on the transparent cover plate near one end thereof. In addition, a retaining projection is formed on the cover near the other end of the window hole, and a retaining recess is formed on the transparent cover plate near the other end thereof.
Thus, according to the present invention, a window hole is formed in the cover, and a transparent cover plate is fitted in the window hole of the cover in such a manner as to be capable of being opened and closed. Therefore, with the cover left attached to the pressure gauge body, the tip of a screwdriver or the like can be brought into contact with the pressure range indicating needles through the window hole when the transparent cover plate is open, to move the pressure range indicating needles.
Further, when the pressure range indicating needles are to be moved, the transparent cover plate is opened, with the cover left attached to the pressure gauge body. Therefore, the positions of the pressure range indicating needles can be moved even when a plurality of pressure gauges are disposed adjacent to each other.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.